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Comparing jsr166/src/jsr166y/ForkJoinPool.java (file contents):
Revision 1.17 by jsr166, Thu Jul 23 23:07:57 2009 UTC vs.
Revision 1.39 by jsr166, Sun Aug 2 17:55:51 2009 UTC

#	Line 5 | Line 5
5		*/
6
7		package jsr166y;
8	<	import java.util.*;
8	>
9		import java.util.concurrent.*;
10	<	import java.util.concurrent.locks.*;
11	<	import java.util.concurrent.atomic.*;
12	<	import sun.misc.Unsafe;
13	<	import java.lang.reflect.*;
10	>
11	>	import java.util.ArrayList;
12	>	import java.util.Arrays;
13	>	import java.util.Collection;
14	>	import java.util.Collections;
15	>	import java.util.List;
16	>	import java.util.concurrent.locks.Condition;
17	>	import java.util.concurrent.locks.LockSupport;
18	>	import java.util.concurrent.locks.ReentrantLock;
19	>	import java.util.concurrent.atomic.AtomicInteger;
20	>	import java.util.concurrent.atomic.AtomicLong;
21
22		/**
23	<	* An {@link ExecutorService} for running {@link ForkJoinTask}s.  A
24	<	* ForkJoinPool provides the entry point for submissions from
25	<	* non-ForkJoinTasks, as well as management and monitoring operations.
26	<	* Normally a single ForkJoinPool is used for a large number of
27	<	* submitted tasks. Otherwise, use would not usually outweigh the
28	<	* construction and bookkeeping overhead of creating a large set of
29	<	* threads.
23	>	* An {@link ExecutorService} for running {@link ForkJoinTask}s.
24	>	* A {@code ForkJoinPool} provides the entry point for submissions
25	>	* from non-{@code ForkJoinTask}s, as well as management and
26	>	* monitoring operations.  Normally a single {@code ForkJoinPool} is
27	>	* used for a large number of submitted tasks. Otherwise, use would
28	>	* not usually outweigh the construction and bookkeeping overhead of
29	>	* creating a large set of threads.
30		*
31	<	* <p>ForkJoinPools differ from other kinds of Executors mainly in
32	<	* that they provide <em>work-stealing</em>: all threads in the pool
33	<	* attempt to find and execute subtasks created by other active tasks
34	<	* (eventually blocking if none exist). This makes them efficient when
35	<	* most tasks spawn other subtasks (as do most ForkJoinTasks), as well
36	<	* as the mixed execution of some plain Runnable- or Callable- based
37	<	* activities along with ForkJoinTasks. When setting
38	<	* {@code setAsyncMode}, a ForkJoinPools may also be appropriate for
39	<	* use with fine-grained tasks that are never joined. Otherwise, other
40	<	* ExecutorService implementations are typically more appropriate
41	<	* choices.
31	>	* <p>{@code ForkJoinPool}s differ from other kinds of {@link
32	>	* Executor}s mainly in that they provide <em>work-stealing</em>: all
33	>	* threads in the pool attempt to find and execute subtasks created by
34	>	* other active tasks (eventually blocking if none exist). This makes
35	>	* them efficient when most tasks spawn other subtasks (as do most
36	>	* {@code ForkJoinTask}s), as well as the mixed execution of some
37	>	* plain {@code Runnable}- or {@code Callable}- based activities along
38	>	* with {@code ForkJoinTask}s. When setting {@linkplain #setAsyncMode
39	>	* async mode}, a {@code ForkJoinPool} may also be appropriate for use
40	>	* with fine-grained tasks that are never joined. Otherwise, other
41	>	* {@code ExecutorService} implementations are typically more
42	>	* appropriate choices.
43		*
44	<	* <p>A ForkJoinPool may be constructed with a given parallelism level
45	<	* (target pool size), which it attempts to maintain by dynamically
46	<	* adding, suspending, or resuming threads, even if some tasks are
47	<	* waiting to join others. However, no such adjustments are performed
48	<	* in the face of blocked IO or other unmanaged synchronization. The
49	<	* nested {@code ManagedBlocker} interface enables extension of
50	<	* the kinds of synchronization accommodated.  The target parallelism
51	<	* level may also be changed dynamically ({@code setParallelism})
52	<	* and thread construction can be limited using methods
53	<	* {@code setMaximumPoolSize} and/or
54	<	* {@code setMaintainsParallelism}.
44	>	* <p>A {@code ForkJoinPool} may be constructed with a given
45	>	* parallelism level (target pool size), which it attempts to maintain
46	>	* by dynamically adding, suspending, or resuming threads, even if
47	>	* some tasks are waiting to join others. However, no such adjustments
48	>	* are performed in the face of blocked IO or other unmanaged
49	>	* synchronization. The nested {@link ManagedBlocker} interface
50	>	* enables extension of the kinds of synchronization accommodated.
51	>	* The target parallelism level may also be changed dynamically
52	>	* ({@link #setParallelism}) and thread construction can be limited
53	>	* using methods {@link #setMaximumPoolSize} and/or {@link
54	>	* #setMaintainsParallelism}.
55		*
56		* <p>In addition to execution and lifecycle control methods, this
57		* class provides status check methods (for example
58	<	* {@code getStealCount}) that are intended to aid in developing,
58	>	* {@link #getStealCount}) that are intended to aid in developing,
59		* tuning, and monitoring fork/join applications. Also, method
60	<	* {@code toString} returns indications of pool state in a
60	>	* {@link #toString} returns indications of pool state in a
61		* convenient form for informal monitoring.
62		*
63		* <p><b>Implementation notes</b>: This implementation restricts the
64		* maximum number of running threads to 32767. Attempts to create
65		* pools with greater than the maximum result in
66	<	* IllegalArgumentExceptions.
66	>	* {@code IllegalArgumentException}.
67		*
68		* @since 1.7
69		* @author Doug Lea
#	Line 74 | Line 82 | public class ForkJoinPool extends Abstra
82		private static final int MAX_THREADS =  0x7FFF;
83
84		/**
85	<	* Factory for creating new ForkJoinWorkerThreads.  A
86	<	* ForkJoinWorkerThreadFactory must be defined and used for
87	<	* ForkJoinWorkerThread subclasses that extend base functionality
88	<	* or initialize threads with different contexts.
85	>	* Factory for creating new {@link ForkJoinWorkerThread}s.
86	>	* A {@code ForkJoinWorkerThreadFactory} must be defined and used
87	>	* for {@code ForkJoinWorkerThread} subclasses that extend base
88	>	* functionality or initialize threads with different contexts.
89		*/
90		public static interface ForkJoinWorkerThreadFactory {
91		/**
#	Line 304 | Line 312 | public class ForkJoinPool extends Abstra
312		}
313
314		/**
315	<	* Returns true if argument represents zero active count and
316	<	* nonzero runstate, which is the triggering condition for
315	>	* Returns {@code true} if argument represents zero active count
316	>	* and nonzero runstate, which is the triggering condition for
317		* terminating on shutdown.
318		*/
319		private static boolean canTerminateOnShutdown(int c) {
#	Line 541 | Line 549 | public class ForkJoinPool extends Abstra
549		* Common code for execute, invoke and submit
550		*/
551		private <T> void doSubmit(ForkJoinTask<T> task) {
552	+	if (task == null)
553	+	throw new NullPointerException();
554		if (isShutdown())
555		throw new RejectedExecutionException();
556		if (workers == null)
#	Line 569 | Line 579 | public class ForkJoinPool extends Abstra
579		* @throws NullPointerException if task is null
580		* @throws RejectedExecutionException if pool is shut down
581		*/
582	<	public <T> void execute(ForkJoinTask<T> task) {
582	>	public void execute(ForkJoinTask<?> task) {
583		doSubmit(task);
584		}
585
586		// AbstractExecutorService methods
587
588		public void execute(Runnable task) {
589	<	doSubmit(new AdaptedRunnable<Void>(task, null));
589	>	ForkJoinTask<?> job;
590	>	if (task instanceof ForkJoinTask<?>) // avoid re-wrap
591	>	job = (ForkJoinTask<?>) task;
592	>	else
593	>	job = ForkJoinTask.adapt(task, null);
594	>	doSubmit(job);
595		}
596
597		public <T> ForkJoinTask<T> submit(Callable<T> task) {
598	<	ForkJoinTask<T> job = new AdaptedCallable<T>(task);
598	>	ForkJoinTask<T> job = ForkJoinTask.adapt(task);
599		doSubmit(job);
600		return job;
601		}
602
603		public <T> ForkJoinTask<T> submit(Runnable task, T result) {
604	<	ForkJoinTask<T> job = new AdaptedRunnable<T>(task, result);
604	>	ForkJoinTask<T> job = ForkJoinTask.adapt(task, result);
605		doSubmit(job);
606		return job;
607		}
608
609		public ForkJoinTask<?> submit(Runnable task) {
610	<	ForkJoinTask<Void> job = new AdaptedRunnable<Void>(task, null);
610	>	ForkJoinTask<?> job;
611	>	if (task instanceof ForkJoinTask<?>) // avoid re-wrap
612	>	job = (ForkJoinTask<?>) task;
613	>	else
614	>	job = ForkJoinTask.adapt(task, null);
615		doSubmit(job);
616		return job;
617		}
618
619		/**
620	<	* Adaptor for Runnables. This implements RunnableFuture
621	<	* to be compliant with AbstractExecutorService constraints.
620	>	* Submits a ForkJoinTask for execution.
621	>	*
622	>	* @param task the task to submit
623	>	* @return the task
624	>	* @throws RejectedExecutionException if the task cannot be
625	>	*         scheduled for execution
626	>	* @throws NullPointerException if the task is null
627		*/
628	<	static final class AdaptedRunnable<T> extends ForkJoinTask<T>
629	<	implements RunnableFuture<T> {
630	<	final Runnable runnable;
607	<	final T resultOnCompletion;
608	<	T result;
609	<	AdaptedRunnable(Runnable runnable, T result) {
610	<	if (runnable == null) throw new NullPointerException();
611	<	this.runnable = runnable;
612	<	this.resultOnCompletion = result;
613	<	}
614	<	public T getRawResult() { return result; }
615	<	public void setRawResult(T v) { result = v; }
616	<	public boolean exec() {
617	<	runnable.run();
618	<	result = resultOnCompletion;
619	<	return true;
620	<	}
621	<	public void run() { invoke(); }
628	>	public <T> ForkJoinTask<T> submit(ForkJoinTask<T> task) {
629	>	doSubmit(task);
630	>	return task;
631		}
632
624	–	/**
625	–	* Adaptor for Callables
626	–	*/
627	–	static final class AdaptedCallable<T> extends ForkJoinTask<T>
628	–	implements RunnableFuture<T> {
629	–	final Callable<T> callable;
630	–	T result;
631	–	AdaptedCallable(Callable<T> callable) {
632	–	if (callable == null) throw new NullPointerException();
633	–	this.callable = callable;
634	–	}
635	–	public T getRawResult() { return result; }
636	–	public void setRawResult(T v) { result = v; }
637	–	public boolean exec() {
638	–	try {
639	–	result = callable.call();
640	–	return true;
641	–	} catch (Error err) {
642	–	throw err;
643	–	} catch (RuntimeException rex) {
644	–	throw rex;
645	–	} catch (Exception ex) {
646	–	throw new RuntimeException(ex);
647	–	}
648	–	}
649	–	public void run() { invoke(); }
650	–	}
633
634		public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks) {
635	<	ArrayList<ForkJoinTask<T>> ts =
635	>	ArrayList<ForkJoinTask<T>> forkJoinTasks =
636		new ArrayList<ForkJoinTask<T>>(tasks.size());
637	<	for (Callable<T> c : tasks)
638	<	ts.add(new AdaptedCallable<T>(c));
639	<	invoke(new InvokeAll<T>(ts));
640	<	return (List<Future<T>>) (List) ts;
637	>	for (Callable<T> task : tasks)
638	>	forkJoinTasks.add(ForkJoinTask.adapt(task));
639	>	invoke(new InvokeAll<T>(forkJoinTasks));
640	>
641	>	@SuppressWarnings({"unchecked", "rawtypes"})
642	>	List<Future<T>> futures = (List<Future<T>>) (List) forkJoinTasks;
643	>	return futures;
644		}
645
646		static final class InvokeAll<T> extends RecursiveAction {
#	Line 665 | Line 650 | public class ForkJoinPool extends Abstra
650		try { invokeAll(tasks); }
651		catch (Exception ignore) {}
652		}
653	+	private static final long serialVersionUID = -7914297376763021607L;
654		}
655
656		// Configuration and status settings and queries
#	Line 682 | Line 668 | public class ForkJoinPool extends Abstra
668		* Returns the handler for internal worker threads that terminate
669		* due to unrecoverable errors encountered while executing tasks.
670		*
671	<	* @return the handler, or null if none
671	>	* @return the handler, or {@code null} if none
672		*/
673		public Thread.UncaughtExceptionHandler getUncaughtExceptionHandler() {
674		Thread.UncaughtExceptionHandler h;
#	Line 703 | Line 689 | public class ForkJoinPool extends Abstra
689		* as handler.
690		*
691		* @param h the new handler
692	<	* @return the old handler, or null if none
692	>	* @return the old handler, or {@code null} if none
693		* @throws SecurityException if a security manager exists and
694		*         the caller is not permitted to modify threads
695		*         because it does not hold {@link
#	Line 777 | Line 763 | public class ForkJoinPool extends Abstra
763		/**
764		* Returns the number of worker threads that have started but not
765		* yet terminated.  This result returned by this method may differ
766	<	* from {@code getParallelism} when threads are created to
766	>	* from {@link #getParallelism} when threads are created to
767		* maintain parallelism when others are cooperatively blocked.
768		*
769		* @return the number of worker threads
#	Line 802 | Line 788 | public class ForkJoinPool extends Abstra
788		* Setting this value has no effect on current pool size. It
789		* controls construction of new threads.
790		*
791	<	* @throws IllegalArgumentException if negative or greater then
791	>	* @throws IllegalArgumentException if negative or greater than
792		* internal implementation limit
793		*/
794		public void setMaximumPoolSize(int newMax) {
#	Line 813 | Line 799 | public class ForkJoinPool extends Abstra
799
800
801		/**
802	<	* Returns true if this pool dynamically maintains its target
803	<	* parallelism level. If false, new threads are added only to
804	<	* avoid possible starvation.
819	<	* This setting is by default true.
802	>	* Returns {@code true} if this pool dynamically maintains its
803	>	* target parallelism level. If false, new threads are added only
804	>	* to avoid possible starvation.  This setting is by default true.
805		*
806	<	* @return true if maintains parallelism
806	>	* @return {@code true} if maintains parallelism
807		*/
808		public boolean getMaintainsParallelism() {
809		return maintainsParallelism;
#	Line 829 | Line 814 | public class ForkJoinPool extends Abstra
814		* parallelism level. If false, new threads are added only to
815		* avoid possible starvation.
816		*
817	<	* @param enable true to maintains parallelism
817	>	* @param enable {@code true} to maintain parallelism
818		*/
819		public void setMaintainsParallelism(boolean enable) {
820		maintainsParallelism = enable;
#	Line 840 | Line 825 | public class ForkJoinPool extends Abstra
825		* tasks that are never joined. This mode may be more appropriate
826		* than default locally stack-based mode in applications in which
827		* worker threads only process asynchronous tasks.  This method is
828	<	* designed to be invoked only when pool is quiescent, and
828	>	* designed to be invoked only when the pool is quiescent, and
829		* typically only before any tasks are submitted. The effects of
830		* invocations at other times may be unpredictable.
831		*
832	<	* @param async if true, use locally FIFO scheduling
832	>	* @param async if {@code true}, use locally FIFO scheduling
833		* @return the previous mode
834	+	* @see #getAsyncMode
835		*/
836		public boolean setAsyncMode(boolean async) {
837		boolean oldMode = locallyFifo;
#	Line 862 | Line 848 | public class ForkJoinPool extends Abstra
848		}
849
850		/**
851	<	* Returns true if this pool uses local first-in-first-out
851	>	* Returns {@code true} if this pool uses local first-in-first-out
852		* scheduling mode for forked tasks that are never joined.
853		*
854	<	* @return true if this pool uses async mode
854	>	* @return {@code true} if this pool uses async mode
855	>	* @see #setAsyncMode
856		*/
857		public boolean getAsyncMode() {
858		return locallyFifo;
#	Line 906 | Line 893 | public class ForkJoinPool extends Abstra
893		}
894
895		/**
896	<	* Returns true if all worker threads are currently idle. An idle
897	<	* worker is one that cannot obtain a task to execute because none
898	<	* are available to steal from other threads, and there are no
899	<	* pending submissions to the pool. This method is conservative;
900	<	* it might not return true immediately upon idleness of all
901	<	* threads, but will eventually become true if threads remain
902	<	* inactive.
896	>	* Returns {@code true} if all worker threads are currently idle.
897	>	* An idle worker is one that cannot obtain a task to execute
898	>	* because none are available to steal from other threads, and
899	>	* there are no pending submissions to the pool. This method is
900	>	* conservative; it might not return {@code true} immediately upon
901	>	* idleness of all threads, but will eventually become true if
902	>	* threads remain inactive.
903		*
904	<	* @return true if all threads are currently idle
904	>	* @return {@code true} if all threads are currently idle
905		*/
906		public boolean isQuiescent() {
907		return activeCountOf(runControl) == 0;
#	Line 980 | Line 967 | public class ForkJoinPool extends Abstra
967		}
968
969		/**
970	<	* Returns true if there are any tasks submitted to this pool
971	<	* that have not yet begun executing.
970	>	* Returns {@code true} if there are any tasks submitted to this
971	>	* pool that have not yet begun executing.
972		*
973		* @return {@code true} if there are any queued submissions
974		*/
#	Line 994 | Line 981 | public class ForkJoinPool extends Abstra
981		* available.  This method may be useful in extensions to this
982		* class that re-assign work in systems with multiple pools.
983		*
984	<	* @return the next submission, or null if none
984	>	* @return the next submission, or {@code null} if none
985		*/
986		protected ForkJoinTask<?> pollSubmission() {
987		return submissionQueue.poll();
#	Line 1017 | Line 1004 | public class ForkJoinPool extends Abstra
1004		* @param c the collection to transfer elements into
1005		* @return the number of elements transferred
1006		*/
1007	<	protected int drainTasksTo(Collection<ForkJoinTask<?>> c) {
1007	>	protected int drainTasksTo(Collection<? super ForkJoinTask<?>> c) {
1008		int n = submissionQueue.drainTo(c);
1009		ForkJoinWorkerThread[] ws = workers;
1010		if (ws != null) {
#	Line 1083 | Line 1070 | public class ForkJoinPool extends Abstra
1070		public void shutdown() {
1071		checkPermission();
1072		transitionRunStateTo(SHUTDOWN);
1073	<	if (canTerminateOnShutdown(runControl))
1073	>	if (canTerminateOnShutdown(runControl)) {
1074	>	if (workers == null) { // shutting down before workers created
1075	>	final ReentrantLock lock = this.workerLock;
1076	>	lock.lock();
1077	>	try {
1078	>	if (workers == null) {
1079	>	terminate();
1080	>	transitionRunStateTo(TERMINATED);
1081	>	termination.signalAll();
1082	>	}
1083	>	} finally {
1084	>	lock.unlock();
1085	>	}
1086	>	}
1087		terminateOnShutdown();
1088	+	}
1089		}
1090
1091		/**
#	Line 1094 | Line 1095 | public class ForkJoinPool extends Abstra
1095		* method may or may not be rejected. Unlike some other executors,
1096		* this method cancels rather than collects non-executed tasks
1097		* upon termination, so always returns an empty list. However, you
1098	<	* can use method {@code drainTasksTo} before invoking this
1098	>	* can use method {@link #drainTasksTo} before invoking this
1099		* method to transfer unexecuted tasks to another collection.
1100		*
1101		* @return an empty list
#	Line 1454 | Line 1455 | public class ForkJoinPool extends Abstra
1455		}
1456
1457		/**
1458	<	* Returns true if worker waiting on sync can proceed:
1458	>	* Returns {@code true} if worker waiting on sync can proceed:
1459		*  - on signal (thread == null)
1460		*  - on event count advance (winning race to notify vs signaller)
1461		*  - on interrupt
#	Line 1462 | Line 1463 | public class ForkJoinPool extends Abstra
1463		* If node was not signalled and event count not advanced on exit,
1464		* then we also help advance event count.
1465		*
1466	<	* @return true if node can be released
1466	>	* @return {@code true} if node can be released
1467		*/
1468		final boolean syncIsReleasable(WaitQueueNode node) {
1469		long prev = node.count;
#	Line 1481 | Line 1482 | public class ForkJoinPool extends Abstra
1482		}
1483
1484		/**
1485	<	* Returns true if a new sync event occurred since last call to
1486	<	* sync or this method, if so, updating caller's count.
1485	>	* Returns {@code true} if a new sync event occurred since last
1486	>	* call to sync or this method, if so, updating caller's count.
1487		*/
1488		final boolean hasNewSyncEvent(ForkJoinWorkerThread w) {
1489		long lc = w.lastEventCount;
#	Line 1566 | Line 1567 | public class ForkJoinPool extends Abstra
1567		}
1568
1569		/**
1570	<	* Returns true if a spare thread appears to be needed.  If
1571	<	* maintaining parallelism, returns true when the deficit in
1570	>	* Returns {@code true} if a spare thread appears to be needed.
1571	>	* If maintaining parallelism, returns true when the deficit in
1572		* running threads is more than the surplus of total threads, and
1573		* there is apparently some work to do.  This self-limiting rule
1574		* means that the more threads that have already been added, the
#	Line 1735 | Line 1736 | public class ForkJoinPool extends Abstra
1736
1737		/**
1738		* Interface for extending managed parallelism for tasks running
1739	<	* in ForkJoinPools. A ManagedBlocker provides two methods.
1740	<	* Method {@code isReleasable} must return true if blocking is not
1741	<	* necessary. Method {@code block} blocks the current thread if
1742	<	* necessary (perhaps internally invoking {@code isReleasable}
1743	<	* before actually blocking.).
1739	>	* in {@link ForkJoinPool}s.
1740	>	*
1741	>	* <p>A {@code ManagedBlocker} provides two methods.
1742	>	* Method {@code isReleasable} must return {@code true} if
1743	>	* blocking is not necessary. Method {@code block} blocks the
1744	>	* current thread if necessary (perhaps internally invoking
1745	>	* {@code isReleasable} before actually blocking.).
1746		*
1747		* <p>For example, here is a ManagedBlocker based on a
1748		* ReentrantLock:
#	Line 1763 | Line 1766 | public class ForkJoinPool extends Abstra
1766		* Possibly blocks the current thread, for example waiting for
1767		* a lock or condition.
1768		*
1769	<	* @return true if no additional blocking is necessary (i.e.,
1770	<	* if isReleasable would return true)
1769	>	* @return {@code true} if no additional blocking is necessary
1770	>	* (i.e., if isReleasable would return true)
1771		* @throws InterruptedException if interrupted while waiting
1772		* (the method is not required to do so, but is allowed to)
1773		*/
1774		boolean block() throws InterruptedException;
1775
1776		/**
1777	<	* Returns true if blocking is unnecessary.
1777	>	* Returns {@code true} if blocking is unnecessary.
1778		*/
1779		boolean isReleasable();
1780		}
1781
1782		/**
1783		* Blocks in accord with the given blocker.  If the current thread
1784	<	* is a ForkJoinWorkerThread, this method possibly arranges for a
1785	<	* spare thread to be activated if necessary to ensure parallelism
1786	<	* while the current thread is blocked.  If
1787	<	* {@code maintainParallelism} is true and the pool supports
1788	<	* it ({@link #getMaintainsParallelism}), this method attempts to
1789	<	* maintain the pool's nominal parallelism. Otherwise it activates
1790	<	* a thread only if necessary to avoid complete starvation. This
1791	<	* option may be preferable when blockages use timeouts, or are
1792	<	* almost always brief.
1784	>	* is a {@link ForkJoinWorkerThread}, this method possibly
1785	>	* arranges for a spare thread to be activated if necessary to
1786	>	* ensure parallelism while the current thread is blocked.
1787	>	*
1788	>	* <p>If {@code maintainParallelism} is {@code true} and the pool
1789	>	* supports it ({@link #getMaintainsParallelism}), this method
1790	>	* attempts to maintain the pool's nominal parallelism. Otherwise
1791	>	* it activates a thread only if necessary to avoid complete
1792	>	* starvation. This option may be preferable when blockages use
1793	>	* timeouts, or are almost always brief.
1794		*
1795	<	* <p> If the caller is not a ForkJoinTask, this method is behaviorally
1796	<	* equivalent to
1795	>	* <p>If the caller is not a {@link ForkJoinTask}, this method is
1796	>	* behaviorally equivalent to
1797		*  <pre> {@code
1798		* while (!blocker.isReleasable())
1799		*   if (blocker.block())
1800		*     return;
1801		* }</pre>
1802	<	* If the caller is a ForkJoinTask, then the pool may first
1803	<	* be expanded to ensure parallelism, and later adjusted.
1802	>	*
1803	>	* If the caller is a {@code ForkJoinTask}, then the pool may
1804	>	* first be expanded to ensure parallelism, and later adjusted.
1805		*
1806		* @param blocker the blocker
1807	<	* @param maintainParallelism if true and supported by this pool,
1808	<	* attempt to maintain the pool's nominal parallelism; otherwise
1809	<	* activate a thread only if necessary to avoid complete
1810	<	* starvation.
1807	>	* @param maintainParallelism if {@code true} and supported by
1808	>	* this pool, attempt to maintain the pool's nominal parallelism;
1809	>	* otherwise activate a thread only if necessary to avoid
1810	>	* complete starvation.
1811		* @throws InterruptedException if blocker.block did so
1812		*/
1813		public static void managedBlock(ManagedBlocker blocker,
#	Line 1828 | Line 1833 | public class ForkJoinPool extends Abstra
1833		do {} while (!blocker.isReleasable() && !blocker.block());
1834		}
1835
1836	<	// AbstractExecutorService overrides
1836	>	// AbstractExecutorService overrides.  These rely on undocumented
1837	>	// fact that ForkJoinTask.adapt returns ForkJoinTasks that also
1838	>	// implement RunnableFuture.
1839
1840		protected <T> RunnableFuture<T> newTaskFor(Runnable runnable, T value) {
1841	<	return new AdaptedRunnable(runnable, value);
1841	>	return (RunnableFuture<T>) ForkJoinTask.adapt(runnable, value);
1842		}
1843
1844		protected <T> RunnableFuture<T> newTaskFor(Callable<T> callable) {
1845	<	return new AdaptedCallable(callable);
1845	>	return (RunnableFuture<T>) ForkJoinTask.adapt(callable);
1846		}
1847
1848	+	// Unsafe mechanics
1849
1850	<	// Temporary Unsafe mechanics for preliminary release
1851	<	private static Unsafe getUnsafe() throws Throwable {
1852	<	try {
1853	<	return Unsafe.getUnsafe();
1854	<	} catch (SecurityException se) {
1855	<	try {
1856	<	return java.security.AccessController.doPrivileged
1857	<	(new java.security.PrivilegedExceptionAction<Unsafe>() {
1858	<	public Unsafe run() throws Exception {
1859	<	return getUnsafePrivileged();
1860	<	}});
1853	<	} catch (java.security.PrivilegedActionException e) {
1854	<	throw e.getCause();
1855	<	}
1856	<	}
1857	<	}
1858	<
1859	<	private static Unsafe getUnsafePrivileged()
1860	<	throws NoSuchFieldException, IllegalAccessException {
1861	<	Field f = Unsafe.class.getDeclaredField("theUnsafe");
1862	<	f.setAccessible(true);
1863	<	return (Unsafe) f.get(null);
1864	<	}
1865	<
1866	<	private static long fieldOffset(String fieldName)
1867	<	throws NoSuchFieldException {
1868	<	return UNSAFE.objectFieldOffset
1869	<	(ForkJoinPool.class.getDeclaredField(fieldName));
1870	<	}
1871	<
1872	<	static final Unsafe UNSAFE;
1873	<	static final long eventCountOffset;
1874	<	static final long workerCountsOffset;
1875	<	static final long runControlOffset;
1876	<	static final long syncStackOffset;
1877	<	static final long spareStackOffset;
1878	<
1879	<	static {
1880	<	try {
1881	<	UNSAFE = getUnsafe();
1882	<	eventCountOffset = fieldOffset("eventCount");
1883	<	workerCountsOffset = fieldOffset("workerCounts");
1884	<	runControlOffset = fieldOffset("runControl");
1885	<	syncStackOffset = fieldOffset("syncStack");
1886	<	spareStackOffset = fieldOffset("spareStack");
1887	<	} catch (Throwable e) {
1888	<	throw new RuntimeException("Could not initialize intrinsics", e);
1889	<	}
1890	<	}
1850	>	private static final sun.misc.Unsafe UNSAFE = getUnsafe();
1851	>	private static final long eventCountOffset =
1852	>	objectFieldOffset("eventCount", ForkJoinPool.class);
1853	>	private static final long workerCountsOffset =
1854	>	objectFieldOffset("workerCounts", ForkJoinPool.class);
1855	>	private static final long runControlOffset =
1856	>	objectFieldOffset("runControl", ForkJoinPool.class);
1857	>	private static final long syncStackOffset =
1858	>	objectFieldOffset("syncStack",ForkJoinPool.class);
1859	>	private static final long spareStackOffset =
1860	>	objectFieldOffset("spareStack", ForkJoinPool.class);
1861
1862		private boolean casEventCount(long cmp, long val) {
1863		return UNSAFE.compareAndSwapLong(this, eventCountOffset, cmp, val);
#	Line 1904 | Line 1874 | public class ForkJoinPool extends Abstra
1874		private boolean casBarrierStack(WaitQueueNode cmp, WaitQueueNode val) {
1875		return UNSAFE.compareAndSwapObject(this, syncStackOffset, cmp, val);
1876		}
1877	+
1878	+	private static long objectFieldOffset(String field, Class<?> klazz) {
1879	+	try {
1880	+	return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field));
1881	+	} catch (NoSuchFieldException e) {
1882	+	// Convert Exception to corresponding Error
1883	+	NoSuchFieldError error = new NoSuchFieldError(field);
1884	+	error.initCause(e);
1885	+	throw error;
1886	+	}
1887	+	}
1888	+
1889	+	/**
1890	+	* Returns a sun.misc.Unsafe.  Suitable for use in a 3rd party package.
1891	+	* Replace with a simple call to Unsafe.getUnsafe when integrating
1892	+	* into a jdk.
1893	+	*
1894	+	* @return a sun.misc.Unsafe
1895	+	*/
1896	+	private static sun.misc.Unsafe getUnsafe() {
1897	+	try {
1898	+	return sun.misc.Unsafe.getUnsafe();
1899	+	} catch (SecurityException se) {
1900	+	try {
1901	+	return java.security.AccessController.doPrivileged
1902	+	(new java.security
1903	+	.PrivilegedExceptionAction<sun.misc.Unsafe>() {
1904	+	public sun.misc.Unsafe run() throws Exception {
1905	+	java.lang.reflect.Field f = sun.misc
1906	+	.Unsafe.class.getDeclaredField("theUnsafe");
1907	+	f.setAccessible(true);
1908	+	return (sun.misc.Unsafe) f.get(null);
1909	+	}});
1910	+	} catch (java.security.PrivilegedActionException e) {
1911	+	throw new RuntimeException("Could not initialize intrinsics",
1912	+	e.getCause());
1913	+	}
1914	+	}
1915	+	}
1916		}

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